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United States Patent |
5,026,602
|
Kitagawa
|
June 25, 1991
|
Mechanical component consisting of anti-static material
Abstract
Anti-static conductive mechanical components of synthetic resin with a
conductive membrane formed on the surface of the synthetic resin through
evaporation. When static electricity is generated during the operation of
the mechanical components, the conductive membrane, which can be used to
ground the synthetic resin, quickly eliminates the static electricity. The
equipment constructed from the mechanical components can thus prevent
malfunctions caused by static electricity.
Inventors:
|
Kitagawa; Hiroji (Nagoya, JP)
|
Assignee:
|
Kitagawa Industries Co., Ltd. (Nagoya, JP)
|
Appl. No.:
|
398977 |
Filed:
|
August 28, 1989 |
Foreign Application Priority Data
| Sep 19, 1988[JP] | 63-234293 |
Current U.S. Class: |
428/336; 428/450; 428/461; 428/922; 428/926 |
Intern'l Class: |
B32B 015/08 |
Field of Search: |
271/109
428/461,457,336,450,922,926
|
References Cited
U.S. Patent Documents
3926428 | Dec., 1975 | Heldenbrand et al. | 271/109.
|
Foreign Patent Documents |
0081965 | Jul., 1982 | EP | 428/922.
|
2012529 | Jan., 1979 | GB | 428/922.
|
Primary Examiner: Herbert; Thomas J.
Attorney, Agent or Firm: Oliff & Berridge
Claims
I claim:
1. A mechanical component comprising an anti-static material, comprising:
a roller comprised of synthetic rubber and having an elasticity;
a conductive metallic membrane on a surface of the roller such that he
conductive metallic membrane grounds the roller, wherein the conductive
metallic membrane is formed by evaporation, a thickness of the conductive
metallic membrane being between about 1.5-4 .mu.m so that the conductive
metallic membrane does not impair the elasticity of said roller.
2. A mechanical component comprising an anti-static material, comprising:
a belt comprised of synthetic rubber and having an elasticity;
a conductive metallic membrane on a surface of the belt such that the
conductive metallic membrane grounds the belt, wherein the conductive
metallic membrane is formed by evaporation, a thickness of the conductive
metallic membrane being between about 1.5-4 .mu.m so that the conductive
metallic membrane does not impair the elasticity of said belt.
3. A mechanical component as in claim 2 in which the metallic conductive
membrane comprises titanium.
4. A mechanical component comprising an anti-static material according to
claim 2, wherein said membrane further comprises ceramics.
Description
BACKGROUND OF THE INVENTION
This invention relates to a mechanical component comprising anti-static
material. The mechanical component is applied to equipment such as a
copying machine, a facsimile machine, or an electrostatic plotter. Such
equipment makes copies or draws charts using electrostatic adsorption.
Since mechanical components such as gears and pulleys are generally made of
conductive metal, they require no static-prevention measures.
On the other hand, since drive belts, non-driven belts, paper-feed rollers,
and the light carriages of a copying machine require some elasticity, they
are made of synthetic resins such as silicon rubber or hard rubber. When
mechanical components such as the drive belts and the paper-feed rollers
are made from an insulating material like synthetic resin, friction
generates static electricity on the surfaces of the mechanical components.
Consequently, the related-art mechanical component is made of synthetic
resin with conductive fillers such as carbon black or metallic particles
mixed in so that the mechanical component does not become charged with
static electricity.
However, a mechanical component made of synthetic resin containing
conductive fillers will not have sufficient conductivity and will develop
problems.
When carbon black is mixed into synthetic resin, the electric resistivity
of the synthetic resin is reduced, but its mechanical strength is also
reduced. The amount of carbon black added must be carefully regulated.
When the maximum amount of carbon black is mixed into the synthetic resin,
it is difficult to obtain the optimum resistivity for the synthetic resin.
The optimum resistivity for preventing synthetic resin from being charged
with static electricity is between 10.sup.5 and 10.sup.9 ohm.cm. As the
amount of carbon black increases, electric resistivity rapidly decreases
from about 10.sup.10 ohm.cm to about 10.sup.2 ohm cm. Thus, it is
difficult to optimally adjust the electric resistivity when mixing carbon
black into synthetic resin.
The related-art conductive mechanical component, which is made of synthetic
resin mixed with carbon black, has little static-prevention effect and may
allow malfunctions of equipment that uses electrostatic adsorption. For
example, when copying paper that has electrostatically adsorbed toner is
fed by a paper-feed roller, either static electricity on the paper-feed
roller strips the toner from the paper, or the paper sticks to the
paper-feed roller.
Alternatively, the mechanical component can consist of synthetic resin with
metallic particles mixed in. However, metallic particles, which differ
from synthetic resin in specific gravity, cannot be distributed uniformly
in the synthetic resin. For example, when a drive belt is made of
synthetic resin mixed with metallic particles, the electric resistivity of
the driven belt is inconsistent, and the drive belt remains partially
charged with static electricity.
SUMMARY OF THE INVENTION
One object of this invention is to provide a conductive mechanical
component that can eliminate static electricity without impairing the
mechanical properties of synthetic resin as a base material for the
mechanical component.
This object is achieved by this invention, which provides a mechanical
component comprising an anti-static material. The mechanical component is
characterized by a body of the mechanical component, and a conductive
membrane on a surface of the body. The conductive membrane grounds the
body.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of mechanical components embodying this invention
.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In this embodiment, conductive components are used to construct a
paper-feed mechanism for a copying machine or a facsimile machine.
As shown in FIG. 1, a first paper-feed cylinder 2 is located opposite
several auxiliary paper-feed rollers 4 set on a shaft 3. A first belt 8
transmits the rotation of a motor 6 and rotates the first paper-feed
cylinder 2. Paper P is fed along the periphery of the first paper-feed
cylinder 2. Subsequently, when the first paper-feed cylinder 2 rotates, a
second belt 12 rotates several auxiliary paper-feed rollers 10 on a shaft
9, and paper P is fed upward between the auxiliary paper-feed rollers 10
and a second paper-feed cylinder 14.
The base material of the first paper-feed cylinder 2, the auxiliary
paper-feed rollers 4 and 10, and the second paper-feed cylinder 14 is a
silicon rubber that is formed in the shape of a cylinder or a ring by
crosslinking high siloxane polymer. An aluminum layer about two microns
thick is formed on the surface of the silicone rubber by means of
evaporation. The surface resistivity of this aluminum layer is
8.times.10.sup.-2 ohm/cm.sup.2.
Since the cylinders 2 and 14 and the rollers 4 and 10 have uniformly thick
metallic layers formed on their surfaces through evaporation to provide a
low, uniform surface resistivity, static electricity will not develop on
them. In addition, since the surface resistivity is uniform, the surfaces
of the cylinders 2 and 14 and the rollers 4 and 10 will not partially
electrify, thus reliably preventing static problems. Consequently, the
cylinders 2 and 14 and the rollers 4 and 10 will not become charged with
static electricity, and paper P will not wrap around the first paper-feed
cylinder 2, or stick between the first cylinder 2 and rollers 4 or between
the second cylinder 14 and rollers 10. An electrostatic latent image
formed on the paper P will not be disturbed by a charged body or a
photosensitive drum (not shown) while the paper P is fed. Toner, which is
electrostatically adsorbed on the electrostatic latent image, adheres to
the paper P. The cylinders 2 and 14, and the rollers 4 and 10 feed paper
and, at the same time, prevent the quality of copying from deteriorating.
On the other hand, the first belt 8 and the second belt 12 for rotating the
cylinder 2 and the rollers 10, respectively, consist of neoprene rubber. A
1.5 micron thick titanium layer is evaporated onto the surfaces of the
belts 8 and 12. The surface resistivity of the layer is 3.times.10.sup.-1
ohm/cm.sup.2.
As with the aluminum layers on the cylinders 2 and 14 and the rollers 4 and
10, the titanium surface layers protect the belts 8 and 12 from static
electricity. The titanium layer is strong and durable.
The components of this embodiment such as the first and second paper-feed
cylinders 2 and 14, the auxiliary paper-feed rollers 4 and 10, and the
first and second belts 8 and 12 have superior mechanical strength and
durability compared with the prior-art components containing carbon black.
The first and second belts 8 and 12 always have a fixed tension, but
strong material is used to improve the wear resistance of the belts 8 and
12.
Although a specific embodiment of the invention has been described for the
purpose of illustration, the invention is not limited to this embodiment.
This invention includes all embodiments and modifications that come within
the scope of the claims. For example, this invention could be gears,
pulleys, cams, light carriages for copying machines, V-belts, and other
mechanical components. A body of the mechanical component could comprise
silicone rubber, neoprene, and other kinds of synthetic rubber. A
conductive membrane formed on the body could be made from aluminum or
titanium. A two to four micron thick membrane is preferable because such a
membrane is conductive without impairing the elasticity of the body. When
the membrane is evaporated onto the body, ceramics can be added to enhance
the strength of the membrane.
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